In some printers that print on a web of print substrate, a supply roll of print substrate web is held an a spindle and unwound to supply web to the printer. In some printers that print on a web of print substrate, a take-up roll is held on a spindle and wound to take-up web output from the printer. Sometimes multiple rolls of print substrate web are unwound or wound in parallel.
The same part numbers designate the same or similar parts throughout the figures.